diff --git a/multiapps_plugin.go b/multiapps_plugin.go
index 6be8166..1e301c8 100644
--- a/multiapps_plugin.go
+++ b/multiapps_plugin.go
@@ -17,6 +17,9 @@ import (
 // Version is the version of the CLI plugin. It is injected on linking time.
 var Version string = "0.0.0"
 
+// MultiappsUserAgentSuffixOption is the default user agent suffix option. It is injected on linking time.
+var MultiappsUserAgentSuffixOption string = ""
+
 // MultiappsPlugin represents a cf CLI plugin for executing operations on MTAs
 type MultiappsPlugin struct{}
 
@@ -50,6 +53,7 @@ func (p *MultiappsPlugin) Run(cliConnection plugin.CliConnection, args []string)
 	}
 	util.SetCfCliVersion(strings.Join(versionOutput, " "))
 	util.SetPluginVersion(Version)
+	util.SetUserAgentSuffixOption(MultiappsUserAgentSuffixOption)
 	command.Initialize(command.GetPluginCommand().Name, cliConnection)
 	status := command.Execute(args[1:])
 	if status == commands.Failure {
diff --git a/util/user_agent_builder.go b/util/user_agent_builder.go
index 5c81611..f0f0c12 100644
--- a/util/user_agent_builder.go
+++ b/util/user_agent_builder.go
@@ -18,6 +18,9 @@ var pluginVersion string = "0.0.0"
 // cfCliVersion stores the version set from the main package
 var cfCliVersion string = DefaultCliVersion
 
+// userAgentSuffixOption stores the default user agent suffix option set from the main package
+var userAgentSuffixOption string = ""
+
 // SetPluginVersion sets the plugin version for use in User-Agent
 func SetPluginVersion(version string) {
 	pluginVersion = version
@@ -28,6 +31,11 @@ func SetCfCliVersion(version string) {
 	cfCliVersion = version
 }
 
+// SetUserAgentSuffixOption sets the default user agent suffix option for use in User-Agent
+func SetUserAgentSuffixOption(suffix string) {
+	userAgentSuffixOption = suffix
+}
+
 // GetPluginVersion returns the current plugin version
 func GetPluginVersion() string {
 	return pluginVersion
@@ -38,6 +46,11 @@ func GetCfCliVersion() string {
 	return cfCliVersion
 }
 
+// GetUserAgentSuffixOption returns the current user agent suffix option
+func GetUserAgentSuffixOption() string {
+	return userAgentSuffixOption
+}
+
 // BuildUserAgent creates a User-Agent string in the format:
 // "Multiapps-CF-plugin/{version} ({operating system version}) {golang builder version} {custom_env_value}"
 func BuildUserAgent() string {
@@ -61,8 +74,13 @@ func getOperatingSystemInformation() string {
 }
 
 // getCustomEnvValue reads value from custom environment variable with validation
+// Falls back to build-time value if environment variable is not set
 func getCustomEnvValue() string {
 	value := os.Getenv("MULTIAPPS_USER_AGENT_SUFFIX")
+	if value == "" {
+		// Use build-time value as fallback
+		value = userAgentSuffixOption
+	}
 	if value == "" {
 		return ""
 	}
diff --git a/util/user_agent_builder_test.go b/util/user_agent_builder_test.go
index 06e00db..8f42f30 100644
--- a/util/user_agent_builder_test.go
+++ b/util/user_agent_builder_test.go
@@ -325,4 +325,48 @@ var _ = Describe("UserAgentBuilder", func() {
 			Expect(util.GetCfCliVersion()).To(Equal(util.DefaultCliVersion))
 		})
 	})
+
+	Describe("Build-time user agent suffix", func() {
+		var originalSuffix string
+
+		BeforeEach(func() {
+			originalSuffix = util.GetUserAgentSuffixOption()
+			util.SetPluginVersion("1.0.0")
+		})
+
+		AfterEach(func() {
+			util.SetUserAgentSuffixOption(originalSuffix)
+			os.Unsetenv("MULTIAPPS_USER_AGENT_SUFFIX")
+		})
+
+		It("should use build-time suffix when environment variable is not set", func() {
+			buildTimeSuffix := "build-time-suffix"
+			util.SetUserAgentSuffixOption(buildTimeSuffix)
+			os.Unsetenv("MULTIAPPS_USER_AGENT_SUFFIX")
+
+			userAgent := util.BuildUserAgent()
+			Expect(userAgent).To(ContainSubstring(buildTimeSuffix))
+		})
+
+		It("should prioritize environment variable over build-time suffix", func() {
+			buildTimeSuffix := "build-time"
+			envSuffix := "env-override"
+
+			util.SetUserAgentSuffixOption(buildTimeSuffix)
+			os.Setenv("MULTIAPPS_USER_AGENT_SUFFIX", envSuffix)
+
+			userAgent := util.BuildUserAgent()
+			Expect(userAgent).To(ContainSubstring(envSuffix))
+			Expect(userAgent).ToNot(ContainSubstring(buildTimeSuffix))
+		})
+
+		It("should handle empty build-time suffix", func() {
+			util.SetUserAgentSuffixOption("")
+			os.Unsetenv("MULTIAPPS_USER_AGENT_SUFFIX")
+
+			userAgent := util.BuildUserAgent()
+			expectedBase := fmt.Sprintf("Multiapps-CF-plugin/1.0.0 (%s %s) %s (%s)", runtime.GOOS, runtime.GOARCH, runtime.Version(), util.GetCfCliVersion())
+			Expect(userAgent).To(Equal(expectedBase))
+		})
+	})
 })